High-tech, meet low-cost. The synthetic Reactor has a bevy of features–including a heat reflector–crammed into a sub-$200 package. Tester fave: the shiny Omni-Heat liner, which has thousands of tiny silver dots that reflect body heat. “They should have called this thing the Microwave because it heats up the second you get in,” says one notoriously cold sleeper. Combined with Columbia’s Thermix MX insulation, the Reactor kept one tester toasty on nights in the mid-20s in New Hampshire’s White Mountains. “It’s a great bag for someone who’s looking to get into shoulder-season camping without committing big bucks,” he says. Testers praised the Omni-Shield water-resistant shell. “After it rubbed against a soaked tent wall, I just shook the bag and all the moisture came right off,” says one tester. Everyone liked the mid-range fit, which provided plenty of thrashing room that, when combined with the lining, didn’t sacrifice thermal efficiency. So what are the downsides? It’s somewhat heavy and not as packable (19 x 7.5 inches) as others in its range, and some testers complained about limited breathability on nights above 40℉. $189; 2 lbs. 14 oz.; columbia.com